Starting September 1992, an outbreak of poliomyelitis occurred in the Netherlands. Until now a total of 67 cases have been notified. These were the first indigenous cases since 1978. None of the patients had been vaccinated before, and all but one belong to small Protestant groups that refuse vaccination for religious reasons. The age of the patients varies from several days to 61 years (mean age 19) and the male to female ratio is 1.6:1.0. The epidemic is caused by wild poliovirus type 3. Partial genomic sequencing showed closest resemblance to a virus isolated in India in 1991. The epidemiological characteristics of the present outbreak are similar to those of previous outbreaks in the seventies. Although vaccination coverage in the Netherlands is excellent (97% coverage for the first series of three doses with IPV vaccine), outbreaks can be expected because some socially closely interrelated small groups refuse vaccination (totalling about 200,000 persons) for religious reasons. Experience from this epidemic, from previous epidemics, and preliminary results of random stool and sewage sampling indicate very little circulating virus among the general population. Changes in (implementation of) the vaccination policy, including a mixed strategy with OPV and IPV, are being considered to reduce the risk of similar outbreaks in the future.